Retracting stop for positioning strip material in a blanking die



Dec. 19, 1967 L. E. MARSZAL 3,358,539

RETRACTING STOP FOR POSITIONING STRIP MATERIAL IN A BLANKING DIE Filed Oct. 22, 1965 2 Sheets-Sheet 1 INVEVNTOR. F 6 Leonard E. Murszol WITNESS Dec. 19, 1967 L. E. MARSZAL 3,358,539

RETRACTING STOP FOR POSIT O ING STRIP MATERIAL IN A BLANK DIE Filed Oct. 22, 1965 2 Sheets-Sheet 2 IIIL.

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United States Patent 3,358,539 RETRACTING STOP FOR POSITIONING STRIP MATERIAL IN A BLANKING DIE Leonard E. Marszal, 1824) Markwood, NW., Grand Rapids, Mich. 49504 Filed Oct. 22, 1965. Ser. No. 501,310 8 Claims. (Cl. 83-391) ABSTRACT OF THE DISCLOSURE A stop coacts with a previously punched hole in strip material to position the strip relative to a blanking die. The stop is spring biased toward the surface of the strip and laterally in a direction opposite to strip advance. Advance of the strip subsequent to blanking allows the stop to drop into the hole just formed and engagement of the stop and the trailing edge of the hole determines the new strip position. When retracted from the hole the stop is shifted laterally by the spring a direction opposite to the strip advance causing the stop once again to be supported by the workpiece.

This invention relates to the construction of dies used to cut pieces from strip material. This type of operation is commonly referred to as blanking, and may be combined in the same die with other operations such as drawing or forming at successive stations. Strip material fed into a blanking die must be properly positioned for the first stroke of the press to avoid excessive scrap. The first action of the die results in the removal of a piece from the strip, leaving a hole where the piece had been. The strip is then shifted along its length enough to move the hole out of the area where the punch operates so that the next blank will be complete.

Stop devices to position the advancing strip properly for each stroke of the press are well known. An example of such a device is shown in the patent of Krasberg, Number 2,610,686. The functioning of these devices is complicated by the fact that they operate as stops when the die is open, and yet must not prevent the advance of the strip during the open period. This action is provided by establishing some degree of freedom of lateral movement in the direction of movement of the strip. The stop can then be retracted by descent of the press, and a spring action then urges the stop slightly in the direction opposite to the strip davance. When the die opens, spring action also urges the stop toward extended position. This latter movement, however, is halted by the strip material itself. The lateral shift of the stop as it is withdrawn from the previous hole now causes the stop to be supported on the surface of the strip. Advance of the strip on the next cycle of the feed mechanism causes the stop to drop into the hole just formed, and engagement of the stop with a trailing edge of this hole determines the new strip position. This type of operation is conventional, and the present invention provides a stop structure having improved rigidity, and a more positive control of the predetermined ranges of movements. The device is also readily adjustable to installation on various dies so that it can be purchased as a standard item.

The several features of the invention will be analyzed in detail through discussion of the particular embodiments illustrated in the accompanying drawings. In the drawings:

FIGURE 1 is an end elevation, partially in section, showing the die and the stop device in position to act as an abutment to the advancing strip.

FIGURE 2 is a side elevation corresponding to FIG- URE 1.

FIGURE 3 shows the mechanism of FIGURES 1 and 2, with the die inducing retraction of the stop device.

3,358,539 Patented Dec. 19, 1967 FIGURE 4 is a view on the plane 4-4 of FIGURE 2.

FIGURE 5 is a view on an enlarged scale showing the details of the assembled stop device.

FIGURE 6 is a fragmentary view of the central portion of the assembly shown in FIGURE 5, showing the displacement of the spring on lateral shifting of the stop.

FIGURE 7 is a perspective view of the spring unit producing combined lateral force and torsion.

FIGURE 8 is a view through the stop device, partially in section, showing the functioning position of the stop.

FIGURE 9 is a view similar to FIGURE 8, showing the displaced position of the assembly on lateral shifting of the stop.

FIGURES 10 through 13 illustrate successive positions of the stop device in plan view.

FIGURE 14 is a view showing a modified form of installation.

FIGURE 15 is a plan view showing the base of the stop device.

FIGURE 16 is a section on the plane 16-16 of FIG- URE 15.

FIGURE 17 is a view on the plane 17-17 of FIG- URE 15.

FIGURE 18 is a plan view of the fulcrum pin used in the stop device illustrated in the previous views.

FIGURE 19 is a side elevation of the fulcrum pin shown in FIGURE 18.

FIGURE 20 shows a modified form of the invention.

FIGURE 21 is a section on the plane 21-21 of FIG- URE 20'.

FIGURE 22 shows a side elevation of a fulcrum pin of the type used in the FIGURE 20 modification.

Referring to FIGURE 1 and the related views, the stop device generally indicated at 30 is shown installed on an otherwise conventional die assembly include the upper plate 31, the punch 32 mounted on the upper plate 31, the lower plate 33, the guide pins 34 for maintaining the alignment of the upper and lower plates at the bearings 35, the die block 36, and the stripper plate 37. This assembly is normally mounted in a conventional punch press (not shown) by a group of bolts in the position shown at 38. Descent of the mm of the punch press will result in moving the upper plate 31 downward, carrying the punch 32 through the clearance opening in the stripper plate 37, and into the die block 36 to blank out pieces of material from the strip 39 in cycles of successive operations.

The stop device 30 can be mounted on the stripper plate 37 by screws as shown at 40 and 41, preferably supplemented by the dowels42 and 43. The base 44 of the device is essentially a block of steel machined as best shown in FIGURE 15 to provide the spaced flanges 45 and 46. The beam portion 47 of the stop arm 48 is received between the flanges 45 and 46, and the angularlybent end 49 of the stop arm forms the abutment that actually controls the position of the stock strip 39.

In addition to riding in the space between the base flanges 45 and 46, the beam 47 traverses the lateral opening 50 in the fulcrum pin 51. This pin has a preferably cylindrical peripheral surface 52, and is received in the aligned holes 53 and 54 in the flanges 45 and 46, respectively. It is significant that these holes are not cylindrical in cross section. They are formed by inserting a cutter to form an initially cylindrical hole, followed by rotation of the axis of the milling cutter with respect to the base 44 in a plane parallel to the mounting surface 55, with the rotation therefore being about an axis perpendicular to the axis of the fulcrum pin 50. The vertical dimension of the holes 53 and 54 has a closely-fitting re lationship to the peripheral surface 52 of the fulcrum pin, but the formation of these holes permits the fulcrum pin to shift within a limited sector of freedom of movement J to permit the stop arm 48 to move between the positions shown in FIGURE 10 and FIGURE .11. The holes 53 and 54 may be said to be defined by the surface which is actually an envelope of the movement cylindrical sur-.

face of the milling cutter under the axial displacement described above.

The space between the flanges 45 and 46 must accommodate this lateral shifting of movement, as shown in FIGURE 11. The surfaces 56 and 57 may be considered as clearance surfaces, and the surfaces 58 and 59 serve as abutments determining the active position of the stop device shown in FIGURE 10. The surfaces 5659 are preferably formed by successive passes of a milling cutter as best shown in FIGURES 16 and 17.

When a strip of steel 39 is initially fed into the die assembly, the die will normally be in the open position shown in FIGURE 1. The action of the spring 60 combine's the function of two springs: (a) it urges the stop arm 48 in a counterclockwise direction as viewed in FIG- URE l and (b) it urges the stop arm in a clockwise direction as viewed in FIGURES 10-13. The preferred formation of the spring 60 involves the coils 61 engaging the boss 62 on the fulcrum pin 51, with the tail 63 engaging the hole 64 in the boss. The gripping of the boss by the coils 61 permits the spring to exert a tendency to rotate the fulcrum pin 51 in a clockwise direction about an axis perpendicular to its own axis, as shown in FIG- URES 1013. The engagement of the tail 65 at the opposite end of the spring with a hole in the base 44 of the device also permits the spring 60 to exert a lateral force to produce this torque. The length of the tangential portion 66 is selected to provide this action. This tangential portion also provides a lever arm for the application of torsion about the axis of the fulcrum pin itself to urge the stop arm 48 into the FIGURE 1 position.

As the upper plate 31 moves downward with the descent of the press ram, the adjustable actuator 67 acts against the top surface of the arm 47, rotating the arm about the axis of the fulcrum pin 51 to move the assembly into the FIGURE 3 position, thus retracting the abutment portion 49 of the arm from engagement with the stock strip 39. Either on the initial insertion of the stock strip as shown in FIGURE 10, or by the previous action of the feed mechanism, the stock strip will have pushed the abutment portion 49 so that it assumes the position of FIGURE 10 against the action of the spring 60. When the abutment portion 49 has been withdrawn as shown in FIGURE 3, however, the effect of the spring 60 is to swing the arm into the FIGURE 11 position. Subsequent upward movement of the ram of the press will then permit the spring 60 to urge the arm assembly 48 toward the FIGURE 1 position, which will be interferred with by the presence of the stock strip underneath abutment portion 49, as shown in FIGURE 11. As the stock strip 39 is moved to the left during the feeding operation, the abutment portion 49 will drop into the hole 68 left by the previous blanking operation. The shifting of the stock strip will continue until the abutment portion 49 comes into engagement with the trailing edge 69 of the hole 68, and the force on the strip again moves the arm 48 to the FIGURE 10 position, as shown in FIGURE 13. Preferably, the access hole 70 in the stripper plate 37 is machined at such a position as will provide freedom for the lateral articulation of the arm 48, and also provide an abutment reinforcing the arm 48 by engaging the portion 49 as shown in FIGURES l and 13. If desired, this opening 70 may be formed as shown in FIGURE 14 as the recess 71. The recess, with proper and careful handling of the stock strip, is not necessarily located to reinforce the portion 49 of the stop arm. This is particularly true in cases where the stock strip 39 is comparatively light, and there is small likelihood of there being substantial forces to be resisted by the stop device.

The stop arm 47 may be adjusted with respect to the axis of the fulcrum pin 51 by simply sliding it through the opening 50, with the final position being determined by the locking pin 72. This pin traverses an axial hole 73 in the fulcrum pin 51, and also traverses one of the holes 74 in the arm 47. The formation of the opening 50 in the fulcrum pin to receive the arm 47 may be accomplished by a hroaching operation, after an initial transverse hole is drilled in the fulcrum pin to receive an end of the broach.

In the modification shown in FIGURES -22, the arm 75 is essentially T-shaped in configuration to produce a greater rigidity against lateral forces. The abutment portion 76 performs the same function as the portion 49 of FIGURE 5, and the fulcrum pin 77 has a slot 78 replacing the opening'St} in the pin 51. The assembled relationship of the arm 75 and the pin 77 is shown in FIGURE 21, and this assembly is mounted in a base 79 similar to the showing of FIGURE 15. A locking pin 80 secures the arm 75 in engagement with the fulcrum pin 77, in addition to providing adjustability by engagement with a selected one of the holes 81.

Under normal conditions, the action of the abutment portions 58 and 59 on the base'of the device against the arm 47, or against the central web 82 of the arm 75 in the latter modification of the invention, will provide sufliciently positive location of the stop position of the portion 49 (or 76). Because of the functioning of these abutment portions 58 and 59, it is preferable that they be machined in such a position as to be in parallel engagement with the sides of the arm in the stop position of the device. The clearance surfaces 56 and 57, since they involve only the resistence against forces from the spring 60, can function with point or line contact, as shown in FIGURES 11 and 12. The engagement of the arm with the edges of the ends of the flanges should determine the same position as that of the displaced axis of the fulcrum pin established by the holes 53 and 54. The position of the surfaces of the flanges being somewhat more positive, due largely to necessary clearance between the arm 47 and the opening 50, the freedom provided by the holes 53 and 54 should be at least equal to, and possibly slightly in excess of the freedom defined by the flanges. The engagement of the stock strip with the portion 49, although producing considerable torque about the axis of the arm 47, will be resisted with very limited movement by the confinement of the fulcrum pin within the vertical dimensions of the holes 53 and 54. a

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

I claim:

1. A stop device for installation in conjunction with a reciprocating blanking die, said device comprising:

a base having spaced flanges and aligned holes in said flanges, said holes being defined by the envelope of a cylindrical surface having the axis thereof moved through a predetermined sector about an axis perpendicular to the axis of said cylinder;

a fulcrum pin having end portions rotatably received in said holes, whereby said fulcrum pin is provided with a limited freedom of displacement of its axis insubstantially one plane only, said fulcrum pin having a central portion provided with a transverse opening normally disposed between the said flanges, said central portion being axially receivable in at least one of said holes;

a stop arm received in said fulcrum pin opening;

means securing said arm with respect to said fulcrum pin; and

biasing means urging said arm rotatively about both of said axes.

2. A stop device as defined in claim 1, wherein said arm has at least one transverse hole and said fulcrum pin has a central axial hole, and wherein said means securing said arm includes a locking pin traversing said axial hole and said hole in said arm.

3. A stop device as defined in claim 1, wherein said fulcrum pin has an axial boss on the end thereof, and said biasing means includes a coil spring having one end engaging said boss, and extending laterally from said bossand the other end secured to said base to provide combined side force and torque.

4. A stop device as defined in claim 1, wherein said flanges have abutment portions disposed to engage portions of said arm on predetermined rotary displacement of the axis of said pin.

5. A stop device as defined in claim 4, wherein said flanges and abutments are defined by offset parallel faces.

6. A stop device as defined in claim 1, wherein the transverse opening in said fulcrum pin is in the form of a slot, and said arm has a substantially T-shaped section received in said slot.

7. A stop device as defined in claim 1, wherein said fulcrum pin is substantially cylindrical in configuration, .having a diameter closely fitting the minor dimension of said aligned holes.

8. A stop device for installation in conjunction with a reciprocating blanking die, said device comprising:

a base having spaced flanges and aligned holes in said flanges, said holes being defined by the envelope of a cylindrical surface having the axis thereof moved through a predetermined sector about an axis perpendicular to the axis of said cylinder;

a fulcrum pin having end portions rotatably received in said holes, whereby said fulcrum pin is provided with a limited freedom of displacement of its axis in substantially one plane only, said fulcrum pin having a central portion provided with a transverse opening normally disposed between the said flanges, said central portion being axially receivable in at least one of said aligned holes, said fulcrum pin also having a central axial hole;

a stop arm received in said fulcrum pin opening, said arm having at least one transverse hole;

means securing said arm with respect to said fulcrum pin including a locking pin traversing said central axial hole and said hole in said arm; and

biasing means urging said arm rotatively about both of said axes.

References Cited UNITED STATES PATENTS 2,219,060 10/ 1940 West 83-391 2,633,9l5 5/1953 Dahstrom et al. 83-391 X 2,646,122 7/1953 MacPheat 83391 X 2,749,561 6/1956 Rush 8329l X WILLIAM W. DYER, J 11., Primary Examiner.

JAMES M. MEISTER, Examiner. 

1. A STOP DEVICE FOR INSTALLATION IN CONJUNCTION WITH A RECIPROCATING BLANKING DIE, SAID DEVICE COMPRISING: A BASE HAVING SPACED FLANGES AND ALIGNED HOLES IN SAID FLANGES, SAID HOLES BEING DEFINED BY THE ENVELOPE OF A CYLINDRICAL SURFACE HAVING THE AXIS THEREOF MOVED THROUGH A PREDETERMINED SECTOR ABOUT AN AXIS PERPENDICULAR TO THE AXIS OF SAID CYLINDER; A FULCRUM PIN HAVING END PORTIONS ROTATABLY RECEIVED IN SAID HOLES, WHEREBY SAID FULCRUM PIN IS PROVIDED WITH A LIMITED FREEDOM OF DISPLACEMENT OF ITS AXIS IN SUBSTANTIALLY ONE PLANE ONLY, SAID FULCRUM PIN HAVING A CENTRAL PORTION PROVIDED WITH A TRANSVERSE OPENING NORMALLY DISPOSED BETWEEN THE SAID FLANGES, SAID CENTRAL PORTION BEING AXIALLY RECEIVABLE IN AT LEAST ONE OF SAID HOLES; A STOP ARM RECEIVED IN SAID FULCRUM PIN OPENING; MEANS SECURING SAID ARM WITH RESPECT TO SAID FULCRUM PIN; AND BIASING MEANS URGING SAID ARM ROTATIVELY ABOUT BOTH OF SAID AXES. 